# How much can the average person remember? **URL:** \ **Category:** Factual Questions\ **Created:** [March 19, 2004, 5:31pm UTC](https://boards.straightdope.com/t/how-much-can-the-average-person-remember/235240 "2004-03-19T17:31:14Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![saluki\_fan](https://avatars.discourse-cdn.com/v4/letter/s/b2d939/32.png) [@saluki\_fan](https://boards.straightdope.com/u/saluki_fan)\ **Post date:** [March 19, 2004, 5:31pm UTC](https://boards.straightdope.com/t/how-much-can-the-average-person-remember/235240/1 "2004-03-19T17:31:14Z")
If a person can have a certain memory triggered by seeing or hearing something, does that mean that we remember everything it’s just that we need the memories need to be triggered in order for us to recall them? If this fact is not true, then how much can we remember (and who was smart enough to figure out how to calculate that?!)? Thank You ---
**Author:** ![js\_africanus](https://avatars.discourse-cdn.com/v4/letter/j/87869e/32.png) [@js\_africanus](https://boards.straightdope.com/u/js_africanus)\ **Post date:** [March 19, 2004, 8:51pm UTC](https://boards.straightdope.com/t/how-much-can-the-average-person-remember/235240/2 "2004-03-19T20:51:19Z")
Your question doesn’t have a simple answer. For example, short term memory has a well defined limit of 7 to 9 items; however, multiple items can be grouped so that the limit of how much can be held is arbitrarily high. For long term memory, I don’t recall any limit. With 20 to 100 billion neurons, the number of interconnections is more than the number of molecules in the known universe, or something similarly outrageous. But you have to remember that memory is a weird thing. Example: When shown a phony brochure of Disney World with Bugs Bunny on it, about 1/3 of the people who see it will have a definite memory of seeing Bugs at Disney World. Never mind that he’s a Warner Bros. actor and doesn’t work for Disney. We like to think of ourselves as being bound to our day-to-day use of our brain power. But experimentally, it has been shown that we can do superhuman feats with training. I recall one experiment where the subjects were taught to type 100 wpm and read a novel with good comprehension at the same time. Not type the novel and read it, but type something completely unrelated while reading a novel. I honestly think that your best bet will be to find a learning & memory textbook at the library, and/or a cognitive psychology book. ---
**Author:** ![trudi\_fermelli](https://avatars.discourse-cdn.com/v4/letter/t/839c29/32.png) [@trudi\_fermelli](https://boards.straightdope.com/u/trudi_fermelli)\ **Post date:** [March 19, 2004, 11:33pm UTC](https://boards.straightdope.com/t/how-much-can-the-average-person-remember/235240/3 "2004-03-19T23:33:26Z")
Ummm…I had a great reference on this topic but it seems to have slipped my mind 😕 And I know you all saw that one coming 😃 But seriously, it seems there are quite a few oddities with regard to my memory, like how I can remember conversations verbatim for years, like a movie playing in my head. And being such a strong visual thinker I would memorize the pages in my textbooks to “look at” when testing, which really had nothing to do with developing total cognitive understanding of certain difficult subjects, but helped me score a good grade. Could this be what they refer to as a photographic memory? ---
**Author:** ![js\_africanus](https://avatars.discourse-cdn.com/v4/letter/j/87869e/32.png) [@js\_africanus](https://boards.straightdope.com/u/js_africanus)\ **Post date:** [March 20, 2004, 5:07am UTC](https://boards.straightdope.com/t/how-much-can-the-average-person-remember/235240/4 "2004-03-20T05:07:11Z")
> [@trudi fermelli](#): > > And being such a strong visual thinker I would memorize the pages in my textbooks to “look at” when testing, which really had nothing to do with developing total cognitive understanding of certain difficult subjects, but helped me score a good grade. Could this be what they refer to as a photographic memory? Not could be, is. Photographic memory means that your memory is like looking at a photograph, so some extent. Thing is, that stuff you remember _for sure_ may not be right. Confidence in memory is in _no way_ correlated with accuracy. Confidence in memory and accuracy in memory are orthogonal. Google for Elizabeth Loftus. She has done a lot of ground-breaking research in memory, esp. eye-witness testimony. ---
**Author:** ![BytopianDream](https://avatars.discourse-cdn.com/v4/letter/b/9de0a6/32.png) [@BytopianDream](https://boards.straightdope.com/u/BytopianDream)\ **Post date:** [March 20, 2004, 8:59am UTC](https://boards.straightdope.com/t/how-much-can-the-average-person-remember/235240/5 "2004-03-20T08:59:08Z")
From: _Cognitive Psychology: In and Out of the Laboratory_ by _Kathleen M. Galotti_, Third Edition, 2004, Wadsworth Publishing. Short Term Memory: Short term memory is broken into three distinct parts based on the modal model of memory. The phonological loop, where we remember sounds, is about 2 seconds of information for up to 2 minutes depending on if you rehearse the information or not. That is, if you are trying to remember a phone number, but someone is distracting you while you are attempting to remember it, the information will fade by about 2 minutes. If you are able to rehearse it, by repeating it over and over, it can be as long as you rehearse it. The visuospacial sketch pad, where we are able to keep something visualized for a quick rememberance, can store about 1-3 images, depending on personal ability. You are not really able to rehearse the VSSP (the visuospacial sketch pad) since you are constantly bombarded with new visual input which can mask (displace) the information attempting to be remembered. Information in the VSSP can last for about 30 seconds until it decays into uselessness. By using chunking, as **js\_africanus** has stated to group information for easier storage in short term memory, will increase the phonological loop’s storage capacity, it is still limited in ability. First, you can only chunk so much information into one chunk and that information still be useful. Second, you can only store so many chunks before you start forgetting some of them. (Regardless of chunking or not, if all the information is presented at once, people usually forget the middle portions of information. The remembering the beginning and ending is called the primacy and recency effects.) Long Term Memory While the above posters are correct in that the theoretical limit of information that a brain can store could be well-nigh infinite, the brain is limited by the number of neuron synapses (the gaps between individual neurons). The average brain has about 10 (to the) 13th power of synapses. Thus, the theoretical brain could store that many bits of information at once. However, that might just fry your brain. The average number of neuron impulses in a persons lifetime is about 10 (to the) 20th power. Thus, that might be how much a person could theoretically know per lifetime. However again, most people do forget stuff. Thus, the average adult at middle age, about 35, could recall and use 1 billion bits of information. For a more complete (and technical) answer to the long term memory capacity, please refer to: Landauer, T. K. (1986). How much do people remember? Some estimates of the quantity of learned information in long-term memory. _Cognitive Science_. 10, 477-493. Do you feel as though I have answered you sufficiently? ---
**Author:** ![AskNott](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/asknott/32/5790_2.png) [@AskNott](https://boards.straightdope.com/u/AskNott)\ **Post date:** [March 20, 2004, 11:44pm UTC](https://boards.straightdope.com/t/how-much-can-the-average-person-remember/235240/6 "2004-03-20T23:44:49Z")
My good friend Mike remembers every bad thing that ever happened to him. He’s still steamed about every one of them. Believe me, he’s had his share of bad luck. He’s had his share and my share, and your share, too. I’m grateful for that, by golly, but sometimes I get tired of hearing about it. Yeah, and…uh…what was the question? ---
**Author:** ![Captain\_Carrot](https://avatars.discourse-cdn.com/v4/letter/c/f0a364/32.png) [@Captain\_Carrot](https://boards.straightdope.com/u/Captain_Carrot)\ **Post date:** [March 21, 2004, 12:36am UTC](https://boards.straightdope.com/t/how-much-can-the-average-person-remember/235240/7 "2004-03-21T00:36:06Z")
Suppose I memorize pi to 1000 places (as I am in the process of doing). I separate the digits into rows of 50, in five blocks of ten digits per row. At first, these groups are part of my short term memory. By the time a week has passed, they are long term memory. When/How does this happen? ---
**Author:** ![Bob55](https://avatars.discourse-cdn.com/v4/letter/b/e9c0ed/32.png) [@Bob55](https://boards.straightdope.com/u/Bob55)\ **Post date:** [March 21, 2004, 1:42am UTC](https://boards.straightdope.com/t/how-much-can-the-average-person-remember/235240/8 "2004-03-21T01:42:54Z")
My Psychology book says our brains have a storage capacity on the order of 10-12 terrabytes (1 terrabyte = 1000 gigabytes). Not that I have any idea of how they came up with that number. The brain obviously uses some very high compression - like a .jpg saved at 10% quality. While I can picture all of my friends and family in my mind, people I’ve seen thousands of times, I still do not have an image as clear as a picture. But I can recognize everyone of them without a problem. ---
**Author:** ![The\_Tim](https://avatars.discourse-cdn.com/v4/letter/t/ec9cab/32.png) [@The\_Tim](https://boards.straightdope.com/u/The_Tim)\ **Post date:** [March 21, 2004, 2:38am UTC](https://boards.straightdope.com/t/how-much-can-the-average-person-remember/235240/9 "2004-03-21T02:38:49Z")
Thinking about the amount of long term memory is missing the point in some regards. Long term memory isn’t just a sequence of stored events that can be called up at a whim or that you need special cues to get at. Long term memory is a change in the patterns of the brain such that particular neurons are more likely to fire together. In the aggregate this means that certain areas related to perception become more tightly bound together so that when one is activated the others are likely to become active as well. When a single set wins out over others you get a clear memory. Memories become fuzzy because neurons are shared between memories. Likewise false memories occur because there isn’t a universal signal for something that was imagined. There are people who have made calculations about memory capacity. Some go for mathematical formalism, others from what we know about neurology and some based on classical experiments. Regardless most of these are just idle calculations from assumptions and not particularly informative. I’m sure you can find some predictions with google or by looking it up in popular psychology books, or better yet collections of papers on memory. ---
**Author:** ![js\_africanus](https://avatars.discourse-cdn.com/v4/letter/j/87869e/32.png) [@js\_africanus](https://boards.straightdope.com/u/js_africanus)\ **Post date:** [March 21, 2004, 9:03pm UTC](https://boards.straightdope.com/t/how-much-can-the-average-person-remember/235240/10 "2004-03-21T21:03:55Z")
> [@dwalin](#): > > Suppose I memorize pi to 1000 places (as I am in the process of doing). By the time a week has passed, they are long term memory. When/How does this happen? They’re in your long-term memory pretty much right away. Put a block of five digits in you head, say 6 8 5 3 3, and commit it to memory. Now count backward from 100 by 3s. What were the five digits? If you remember, then they’re in your long-term memory. (Obviously, this exercise is a silly example because the numbers are on the screen in front of you; but the point is the same.) Short term memory is like a temporary cache, or maybe a working cache, that gets cleared off after a few seconds if you aren’t actively using it. How does it happen? I don’t know. I only know that the hippacampus (sp?) is involved.